Many microsurgical procedures require precision cutting and/or removal of various body tissues. For example, vitreoretinal surgery often requires the cutting, removal, dissection, delamination, coagulation, or other manipulation of delicate tissues such as the vitreous humor, traction bands, membranes, or the retina. The vitreous humor, or vitreous, is composed of numerous microscopic fibers that are often attached to the retina. Therefore, cutting, removal, or other manipulation of the vitreous must be done with great care to avoid traction on the retina, the separation of the retina from the choroid, a retinal tear, or, in the worst case, cutting and removal of the retina itself.
Microsurgical instruments, such as vitrectomy probes, fiber optic illuminators, infusion cannulas, aspiration probes, scissors, forceps, and lasers are typically utilized during vitreoretinal surgery. These devices are generally inserted through one or more surgical incisions in the sclera near the pars plana, which are called sclerotomies. Generally, a cutting blade disposed within a tubular probe needle moves reciprocally within the probe needle, thereby cutting material, e.g., vitreous humor, with a blade edge that translates relative to an aperture in the needle. At the same time, the humor is drawn away from the cutting site through the aperture. For example, suction may be applied to draw the humor away from the aperture, continuing through the needle.
To minimize the size of the surgical incisions necessary to perform these procedures, probe needles are designed in progressively smaller sizes. As probe size decreases, maximizing fluid flow through the needle becomes increasingly important. The cutting blade, which must be strong enough to resist buckling from the high speed reciprocal motion within the needle, necessarily reduces flow as it obstructs a portion of the needle. Accordingly, there is a need for an improved probe needle that reduces overall size while providing adequate flow through the needle.